IPRS - Internet Phone Radio System 26 July 2002
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WB4APR
IPRS is an acronym to describe the potential of a marriage between
the global APRS digital network and the global Internet Radio
linking project. Combining the first and last letters of IRLP
with the final three letters of APRS yields IPRS!
As APRS grew to global proportions in the late 90's through the
internet connectivity pioneered by Steve Dimse (K4HG), I began
looking for ways to add internet voice connectivity to APRS and
called it AVRS. Over the same period, Dave Cameron's (VE7LTD)
Internet Radio Linking Project has risen to prominance world wide
by providing that same kind of global conectivity as APRS but with
voice.
Taking advantage of the voice connectivity of IRLP, recently we have
defined many ideas and APRS formats to be able to use APRS as an
adjunct data link to facilitate the end-to-end signalling between
end users of IRLP using APRS. Further the mobile APRS data
displays make an excellent function for displaying IRLP network
data to the mobile user. One of the ultimate objectives of the
APRS adjunct to IRLP is the ability of an APRS mobile user to
establish an end-to-end voice connection to any other amateur on the
planet with no other knowledge than his callsign.
Thus, the IRLP system and the APRS-IS (Internet System) could work
together to make the end-to end voice connection using the nearest
available IRLP nodes. At the Radio Amateurs of Canada (RAC) National
convention in Vernon, BC on 26 July, I discussed this concept with Dave
Cameron and suggested we might define this marriage as "IPRS". This
IPRS term will facilitate further discussions about this revolutionary
potential! THe following is 3 phased approach could be used to
arrive at that ultimate objective. The first is MANUAL, the second is
ASSISTED and the third is called AUTO-QSY.
MANUAL - APRS user-to-user Call-back message. (Works now today!)
ASSISTED - Central IPRS server watches global IRLP and APRS-IS system
and when seeing IPRS-CQ, sends APRS-QSY msg to BOTH users
informing them both of the nearest not-in-use IRLP node
numbers and freqs. Users manually QSY and the caller
establishes the IRLP link.
AUTO-QSY - End user's radio, on receipt of the APRS-QSY message, will
AUTOMATICALLY QSY, and central IPRS server will automatically
establish the IRLP node links!
The following paragraphs elaborate on the above phases and add
additional details to this concept.
IPRS-NUMBERING SYSTEMS: Also, we do need to account for the
large number of IRLP spin-offs exploding onto the landscape by using
a consistent numbering system across all applications. The following
APRS messages for now, could suffice for the users to send a call-back
message:
IRLP: CQ I####
I-Link: CQ L####
EchoLink: CQ E#####
eQSO: CQ Q#####
IPRS AHUBS: And having IPRS work across a variety of voice systems also
suggests that instead of IPRS trying to get inside of the internal link
status system of each type system, it might be better to ask all Voice
systems desiring to support APRS end users, to put out their IPRS status
into a COMMON APRS formatted internet IPRS clearing house channel...
An AHUB if you will..
In other words, we put up an APRS-INTERNET-HUB where all IPRS applications
simply send their current status in APRS formatted style packets. This is
an OPEN AHUB, just like all the APRS hubs are and all IPRS applications
can monitor this channel for end user node status for finding active and
available nodes for IPRS requests.
DETAIL DESCRIPTIONS OF IPRS PHASES:
MANUAL - APRS user sends simple message to another APRS user indicating
his call-back IRLP number. APRS recepient initiates IRLP call back.
This works, NOW, TODAY! The format of the APRS message is simply:
From: WB4APR To: VE7LTD Msg: CQI #1234
The meaning is that WB4APR is asking VE7LTD to call him back on his
current IRLP node #1234. The APRS message reaches VE7LTD no matter
where he is on the planet via the APRS-IS assuming he is on the
air. On receipt, and if VE7LTD is available, he will establish the
call-back link.
ASSISTED - A distributed IPRS server system monitors both the IRLP
active node status and also the global APRS-IS stream looking for IPRS-CQ
messages. On detection, it compares the positions of the users and the
nodes and identifies the nearest non-busy IRLP node numbers to each one.
If one of the nearest nodes is connected to a CONFERENCE node, then both
users are invited to join the conference in session. This reply message
to both end users is tailored to fit on each one's APRS message screen.
APRS user: 67 character free field line
TH-D7 HT user: 45 char line arranged as 12,12,12,9
TMD700 user: 64 char line arranged as 22,22,21